This invention relates to data retrieval systems for use on networks.
The so-called world wide web has become a popular medium to deliver information on-line. The world wide web also referred to as the xe2x80x9cInternetxe2x80x9d offers users a simple and intuitive way of browsing multimedia information arranged as web pages. A web page includes information and hyperlinks or connections to other web pages. Pages for delivering information can be implemented on private internets, commonly referred to as xe2x80x9cintranets.xe2x80x9d In either the Internet or intranets, the types of multimedia data that can be accessed has grown from text and bit map images to include sound, digital video, interactive video and virtual reality. Information on the world wide web is presented as multimedia pages and interaction is performed through selecting active elements such as buttons, hyperlinked words, and image maps.
Access to the Internet is generally provided with a client-server computer system model. Generally a server computer provides services such as internet access for client computers. The client computers have web browsers that couple the client computer to the server computer and permit users to access various resources available on the Internet or an intranet. One of the resources can be local or a remote database server having a text-based database or a relational database or other types of databases.
One technique used on the world wide web to access databases uses embedded structured query language commands (SQL) and proprietary language in authored hypertext pages that are parsed by an augmented hypertext server and passed to a database server for execution. Another technique employs templates to specify queries and formatting for database searches. Finally, program gateways such as Hypertext Transfer Protocol Devicexe2x80x94Common Gateway Interface (HTTPD-CGI), the most common gateway interface, allow programs to be executed by the server in response to a hypertext request. While these examples of web-based database access provide fundamental connectivity between hypertext servers and databases, they do not take full advantage of the wide range and rich offerings available on the Internet.
According to one aspect of the invention, a schema base data structure to interface a database to a web browser, permitting the web browser to navigate through the database includes first and second fields for representing referencing and referenced object classes and a relationship field for representing a relationship between the first and second objects. The data structure also includes extraction command fields to retrieve instances of the class from an underlying database and use rules for parsing parameters used in the database retrieval.
According to another aspect of the invention, a method of operating a web browser to retrieve information in a database, in a computer network comprises providing a schema base which represents information in the database as classes of objects and relations between classes of objects, executing one or more search queries for a selected instance of a class object, and generating a web page to place hyperlinks on the page corresponding to relationships between selected objects and object instances in the schema.
According to a further aspect of the invention, a method of operating a web browser to retrieve information in a text-based or a relational database in a computer network includes selecting a named class of objects from a plurality of available named classes of objects contained in a schema base and retrieving relations from the schema base defining the roles played by the selected named object class in relation to roles played with others of the plurality of named object classes contained in the schema base. The method also includes executing one or more search queries for each found named class occurrence from the schema base, retrieving instances of related named objects identified by a relation between the selected named object class and generating a web page to place hyperlinks corresponding to the relationships between the selected named object and other object instances in the schema.
One or more advantages are achieved with the foregoing. Databases such as text-based or relational databases are browsed in a manner that mirrors the interactive browsing of world wide web pages. The schema-based navigational layer dynamically maps data stored in a database onto web pages. The schema base can be reused or derived from the database design process or produced specifically for navigation through the database. Navigating a database in this manner extends the conventional database concept of the logical view to an interactive model of logical view-transitions. The technique is a simple and powerful model for automated access to databases making available vast amounts of data stored in databases for Internet and intranet web browsing.